1. Field of the Invention
The present invention relates to a light emitting diode (LED) package, more particularly, which has a heat conducting part comprised of folded sheet metals and a recess formed thereon to seat an LED chip therein, thereby enhancing reflection efficiency and simplifying an overall process.
2. Description of the Related Art
An LED is a semiconductor apparatus for generating multi-color light when current is supplied. The color of light generated from the LED is largely determined by chemical components of the LED semiconductor. The LED is more advantageous than a filament-based light emitting device, thus exhibiting a longer useful life, a low voltage, excellent initial driving properties, high vibration resistance and higher tolerance against repetitive power switching, and the like. Accordingly, demand for the LED has been steadily rising.
Recently the LED is employed in a lighting device and a backlight device for a large-scale Liquid Crystal Display (LCD). Due to a big output requirement of the devices, the LED needs to have a package structure with superior heat release properties.
FIG. 1(a) is a view illustrating a conventional LED package, and FIG. 1(b) is a view illustrating the LED package mounted on a circuit board.
First, referring to FIG. 1(a), the LED package 10 includes a heat slug or heat conducting part 14 which has an LED chip 12 mounted therein and serves to guide heat. The LED chip 12 is supplied with electricity from external power (not illustrated) through a pair of wires 16 for supplying power and a pair of terminals 18. An upper part of the heat conducting part 14 including the LED chip 12 is encapsulated by an encapsulant 20 generally made of silicone. The encapsulant 20 is covered with a lens 22. A housing 24 is formed around the heat conducting part 14 typically by molding, thereby supporting the heat conducting part 14 and the terminals 18.
The LED package 10 of FIG. 1(a) is mounted on a circuit board 30 which is a heat sink to constitute an LED assembly 40. Here, a heat conductive pad 36 such as a solder is inserted between the heat conducting part 14 of the LED package 10 and a heat releasing metal substrate 32 of the circuit board 30, thus facilitating heat conductivity therebetween. Moreover, the terminals 18 are solidly connected to a circuit pattern 34 of the circuit board 30 via a solder 38.
The LED package 10 and the LED assembly 40 having the LED package mounted on the circuit board 30 as shown in FIG. 1 are aimed to release heat to a great extent. That is, for the LED package 10 to absorb heat generated from the LED chip 12 and release it to the outside, the heat sink, i.e., the heat conducting part 14 is connected to a heat releasing substrate 32 of the circuit board 30 either through a heat conductive pad 36 or directly. This allows heat generated in the LED chip 12 to be mostly conducted through the heat conducting part 14 to the heat releasing substrate 32 of the circuit board 30. Only a small portion of heat is released into the air through the surface of the LED package, i.e., the housing 24 or the lens 22.
However, such a conventional heat releasing structure is too complicated to be automated and necessitates assembling of too many parts and components. This disadvantageously increases production cost.
FIG. 2 illustrates an LED lead frame structure disclosed in U.S. Patent Application Publication No. 2004/0075100. FIG. 2 depicts a lead frame 2 and a heat conducting part 4. The lead frame 2 is separated into two electric connecting parts 12a and 12b, which are connected to respective solder connecting strips 3a and 3b. 
The first electric connecting part 12a has an eye-shaped opening into which the heat conducting part 4 is inserted. The heat conducting part 4 is substantially rotationally symmetric and has protrusions formed thereon to ensure the lead frame is solidly fixed inside a housing. The heat conducting part 4 has a recess formed in the center thereof to serve as a reflector 16. Also, on a bottom surface of the heat conducting part 4, a chip mounting area 11 is provided to support a light releasing chip, which is the LED chip. A side of the recess functions as a reflecting surface.
The eye-shaped opening of the first electric connecting part 12a has a cut 13 abutting a tongue-shaped bonding wire connecting area 10 of the second electric connecting part 12b. The bonding wire connecting area 10 is disposed at a height different from that of an outer periphery of the reflector 16 for emitting light. This structure obviates a need for cutting out the outer periphery of the reflector 16 to seat a chip but allows the chip and the bonding wire connecting area 10 to be connected via a short wire.
Meanwhile, reference sign 27 denotes a light emitting direction.
Such a lead frame structure allows a package body to be molded of resin with the first electric connector 12a inserted into the heat conducting part 4. Therefore, this ensures a simpler manufacturing process than the package structure explained with reference to FIG. 1.
But this lead frame structure is disadvantageously limited to a case where the electric connecting part 12a and the heat conducting part 4 are electrically connected with each other, as the first electric connecting part 12a is in direct contact with the heat conducting part 4. That is, such a structure cannot be employed in a case where the electric connecting part 12a and the heat conducting part 4 are insulated from each other.
Also, the heat conducting part 4 and the electric connecting part 12a are necessarily assembled together due to their separate manufacturing. Moreover, the assembled heat conducting part 4 and the electric connecting part 12a are separated from each other and electrodes are easily shorted when external impact is applied.